Fifth edition WHO classification: mature B-cell neoplasms.

We present a review of mature B-cell neoplasms as described in the fifth edition of the WHO classification of haematolymphoid tumours (WHO-HAEM5). Entities have expanded, and definitions are increasingly reliant on genomic and other technologies. However, the WHO-HAEM5 employs a hierarchical structure with family (class)-level definitions that group several specific entities. This approach enables the assignment of a family-level diagnosis when criteria for specific entities cannot be met due to resource constraints. To facilitate application in resource-limited settings, WHO-HAEM5 divides diagnostic criteria into 'essential' and desirable criteria for most entities. This review focuses on changes and updates in B-cell lymphoma classification, providing guidance on how to apply the WHO classification in resource-limited settings.